Penberthy & Penberthy-Pierson(a.k.a. Valdôtain)

Larry
Penberthy (Off Belay No. 16, pp. 10-11) introduced
this knot as a rappel safety (I discussed this use in my
1995 Rappel Safeties
Internet Post), but our interest here is in its use as a climbing
knot. The knot is the Penberthy if you tie the ends of the sling
together and clip the loop, and the Penberthy-Pierson or Valdôtain
when you clip loops tied in the the free ends. Some people won't
call it a Valdôtain if it does not have exactly seven turns.
I prefer not to quibble over any of these nuances in the nomenclature,
since very few people use the names consistently.

The truth is, these are just variations of the Helical
Knot, although they leave more slack than the classical method,
resulting in knots that slide - and slip - more easily. Compensate
by adding turns.

Note:The performance of any ascending knot depends on the diameter, material,
construction, and condition of both the main line and the ascender knot sling material. It may
also depend on exactly how one ties the knot. Your knot's performance can easily differ from mine.